Olefinic resins have excellent mechanical strength, moldability and chemical resistance, and are used in various commercial fields, such as in interior or exterior parts of automobiles, electric appliance parts and housings. However, polyolefines are nonpolar molecules and, therefore, have problems in secondary processing, particularly in adhesion and painting in a solid state. To improve such olefinic resins, polystyrene which has good adhesive property was blended to olefinic resins.
Among polystyrenic resins, styrene-acrylonitrile copolymers are excellent in chemical resistance, strength and heat resistance and, accordingly, blends thereof with olefinic resins were expected to exhibit various good properties.
However, olefinic resins are less compatible with styrenic resins. Therefore, blends of these suffer from decreased physical properties, particularly decrease in surface peeling resistance.
Accordingly, various compositions in which a compatibilizer is added to a composition of a polypropylene resin and a polystyrenic resin were proposed in order to improved their compatibility (Japanese Patent Application Laid-Open Nos. Sho-64-87945/1989 and Hei-1-174550/1989). All of these compositions contain styrene-non-conjugated diene block copolymers or the like.
Although the above compatibilizers can exhibit some degree of effects in compatibilization between polypropylene resins and polystyrenic resins, they have, however, almost no effect in compatibilization between polypropylene resins and styrene-acrylonitrile copolymers.
As mentioned above, it was impossible to obtain a composition of olefinic resins and styrene-acrylonitrile copolymers in which both are well compatibilized.